1. Human Genetic Disorders
The following is a presentation of several human genetic disorders. Some of the pictures may be disturbing. Please keep in mind that these photographs are taken to assist the medical field in correctly diagnosing genetic disorders.
Photos are from Smith’s Recognizable Patterns of Human Malformation, Chromosome Abnormalities, and Genetic Counseling, Genetics In Medicine.

2. Human Genetic Disorders
Many of the disorders that will be discussed during this presentation are in extremely low frequency in the population. This means that very few individuals in the world suffer from these disorders.

3. Human Genetics Gene Heredity
The passing-down of traits from parent to child through genes, which are located in chromosomes.
Gene

4. Pedigree
A diagram that shows the pattern of inheritance of a gene in a family.

5. Sex-Linked Traits Traits carried by X or Y chromosome
Example: Colorblindness .. Carried on X chromosome
genotypes…
Why is it more common in males?

6. Genetic Disorders Types of Genetic Disorders
Autosomal Recessive Genetic Disorders
Autosomal Dominant Genetic Disorders
Nondisjunction Genetic Disorders
Sex-Linked Nondisjunction Genetic Disorders

7. Autosomal Recessive Genetic Disorders
Cystic fibrosis
Phenylketonuria
Galactosemia
(1:18000)
(1:55000)
(1:3900)
On chromosome 7
On chromosome 12
On chromosome 9
Affects ability to break down galactose
Affects respiratory / digestive sys.
affects how body breaks down protein.
Mutation in gene that affects salt movement, thus produces thick sticky mucous on outside of cell. This mucous clogs airways
Lack enzyme called GATL (which converts galactose into glucose). Galactose build up in the blood.
prevents liver enzyme (PAH) from breaking down phenylalanine., which builds up in blood & poisons nerve cells in brain.

8. Autosomal DominantGenetic Disorders
Breast Cancer
Huntington's
Colon Cancer
(5-10% of patients)
(1:30000)
(~80% of patients)
On chromosome 17 or 13
On chromosome 4
On chromosome 5
brain disorder that affects a person's ability to think, talk, and move.
Have family history – at greater risk ;
risk increases when a relative got it before 50--high-risk, because may have inherited one rare genetic condition: FAP (familial adenomatous polyposis).
Rarely inherited … but can inherit gene
have a high #of CAG triplets (>40). Somehow brain cells accumulate clumps of protein that become toxic. Some patients lose > 25% of their brain cells before they die.

9. Aneuploidy Abnormal number of chromosomes
Trisomy disorders are considered major chromosomal abnormalities that involve the addition of an extra chromosome or part of a chromosome. Most individuals will only have two copies of a single chromosome one that was received from Mom and one received from Dad.
These disorders are caused by a nondisjunction during the process of meiosis and other factors.
1/5 of all conceptions and about 1/2 of all spontaneous abortions have chromosome abnormalities

10. Nondisjunction
When chromosomes don't separate properly during meiosis.
results in gametes w/ too many or few chromosomes.

11. Nondisjunction Genetic Disorders
Downs syndrome/Trisomy 21
Patau syndrome/Trisomy 13
Edwards syndrome/Trisomy 18

12. Trisomy 21 / Down Syndrome
(1:800)
Individuals have partial or total addition of chromosome number 21
Symptoms
Mental retardation distinctive eyes
enlarged tongue short stature
enlarged heart low body tone
decreased life expectancy small ears
Slanted palpebral Fissures Flat face

13. Trisomy 21

14. Trisomy 13 – Patau syndrome
(1:10000)
Symptoms
defects of eye, nose, lip, and forebrain
Polydactyly (more then 5 fingers or toes)
hyperconvex fingernails (arches down)
Only 18% survive the first year
Survivors have severe mental defects
seizures

15. Trisomy 13

16. Trisomy 18- Edwards syndrome
(1:3000)
Clenched hand
Distinct patterns on the fingertip
Low Arch Dermal - the crease on tip the 5th finger is missing.
80% die w/in first two months
Only 10% survive the first year
Usually feeble (weakness)
Limited capacity for survival
Resuscitation (artificial breathing) often performed at birth
apneic episodes neonatally (stop breathing during sleep)

17. Trisomy 18

18. Trisomy Disorders
Almost all other trisomy situations result in death of the fetus
Trisomy means there are 3 chromosomes in one location

19. Triploidy and Tetraploidy
1-2% of all pregnancies
Scarcely any triploids are born alive
Arise from double fertilization

20. Sex linked Nondisjunction Genetic Disorders
Turner syndrome
Klinefelter syndrome
Fragile-X syndrome

21. Sex Chromosome Abnormalities
A normal female has two X chromosomes
A normal male has an X and a Y chromosome
There are several disorders where additional sex chromosomes are present

22. Turner Syndrome Females with only one X sex chromosomes
Physical Characteristics
Short stature
Web neck
Infertile
Normal intelligence
Low posterior hairline
broad chest with widely spaced nipples
elevated frequency of renal (kidney) and cardiovascular anomalies

23. Turner Syndrome

24. Klinefelter Syndrome XXY
First sex chromosome abnormality to be reported
Tall, thin relatively long legs
appear normal until puberty
Hypogonadism (sex hormones are not released)
Infertile due to undeveloped sex orgnas
significantly reduced IQ

25. Klinefelter Syndrome
                      

26. Fragile X Syndrome Females who carry the trait may also show symptoms
In males the lower portion of the X chromosome appears constricted in a karyotype.
Moderate mental retardation
Fragile site - chromatin fails to condense during mitosis
Females who carry the trait may also show symptoms
long face with a prominent jaw, large prominent ears, high arched palate; flattened nasal bridge; Prominent forehead .

27. Fragile X Syndrome

28. Fragile x syndrome is like Autism
Developmental delay, speech delay, short attention span or hyperactivity, mouthing of objects persisting at an age beyond expected, difficulty in disciplining the child, frequent temper tantrums, autistic-like behaviors such as rocking, talking to oneself, spinning, unusual hand movements, difficulty with transitions, preference for being alone, echolalia, poor eye contact; poor motor coordination; history of vomiting, spitting up or colic during infancy; history of self-abusive behavior; hand flapping; drooling persisting beyond expected; increase fighting with others; hand/thumb sucking.

29. General Human Genetic Disorders

30. Achondroplasia Dwarfism- small stature Large head Skeletal disorders
Narrow nasal passages
Respiratory problems
90% of cases are fresh mutations
Older paternal age is a contributing factor to mutation

31. Achondroplasia

32. Marfan Syndrome Tall stature with long slim limbs Low tone muscles
Little subcutaneous or skin fat
60% scoliosis
Heart disorders (thought that Abraham Lincoln had this disorder)

33. Marfan Syndrome

34. Progeria Syndrome
Hutchinson-Gilford Progeria Syndrome or premature aging disease.
Noticeable months of age.
Life expectancy 8-21 years with an average of 14 years
Research on these individuals are done to help us understand the aging process

35. Progeria Syndrome Aged looking skin Growth failure Hip dislocation
Arthritis, joint stiffness
Cardiovascular atherosclerosis disease and stroke, eventually leading to death.
Enlarged heart and high blood pressure
Not specific to sex or ethnicity

36. Progeria Syndrome
                                                                        

37. Taratogens
Any agent that can produce a malformation or raise the population incidence of a malformation.
Most known teratogens are infectious agents, radiation or drugs (alcohol, cocaine, Tetracycline and Streptomycin- antibiotic, Anticonvulsants)

38. FAS (Fetal Alcohol Syndrome)
Maternal alcohol consumption
Major cause of mental retardation
Growth retardation
Skeletal defects
Heart defects
Flat fultrum
enlarged head
neurological disorders

39. FAS

41. Metabolic Disorders
These disorders are characteristic of a breakdown of a biochemical pathway which can cause minor problems or major problems.
Several of these disorders

42. Tay’sachs
Blindness
Severe mental and physical deterioration (normal to 6 months).
A missing enzyme causes progressive nerve cell damage.
Leading to seizures and paralysis.
Death in early childhood by 5 years of age.
Lethal autosomal recessive disorder with high frequency in a specific, genetically isolated population
first disorder where large scaled screening was performed

43. 3-5 year old with advanced Taysachs
Goggle.com

44. Phenylketonuria (PKU)
Autosomal recessive trait.
Causes severe mental retardation, skin rashes, irritable behavior, musty body odor.
Cannot degrade the amino acid phenylalanine which accumulates in body fluids preventing the brain from growing and developing normally.
1/10,000 live births
Colorado performs a mandatory test for all newborns (heal prick)
A strict non-animal protein diet must be followed (eggs, meat, milk etc.) throughout adolescence and possibly adulthood.
Blood is monitored for ones whole life.

45. Phenylketonuria (PKU)

46. Genomic Imprinting
The expression of the disease phenotype depends on whether it has been inherited from the father or from the mother.
Prader-Willi Syndrome vs. Angelman’s Syndrome

47. Prader-Willi Syndrome
Obesity
Small hands and feet
Short stature
Mental retardation
Do not produce the chemical that tells them they are full
Severely over weight
Their crave for food can be so server that parents have to lock their refrigerators
Inherited from the mother

48. Angelman’s Syndrome “Happy Puppets” disorder Mental Retardation
Can understand only simple commands
Inappropriate laughter

49. Use your knowledge to be compassionate and kind towards others.
This is the end….
Use your knowledge to be compassionate and kind towards others.